1. Field of the Invention
The present invention relates to a resin sealing method and a resin sealing apparatus for electrically connecting electrodes provided on a substrate and a semiconductor chip fixed to the substrate with each other and thereafter sealing the semiconductor chip and the substrate with resin, and more particularly, it relates to a resin sealing method and a resin sealing apparatus excellent in workability.
2. Description of the Prior Art
In recent years, miniaturization is strongly required to a package having a semiconductor chip. Therefore, the so-called CSP (chip size package) is widely employed. Further, a BOC (board on chip) type CSP is employed in order to minimize the lengths of wires in the package for satisfying requirement for a high-speed operation of an electronic apparatus. In the BOC type CSP, a substrate having an opening is placed on a semiconductor chip so that a pad provided on the upper surface of the substrate is connected with a pad provided on the upper surface of the semiconductor chip through the opening with a wire or a metal strip.
Conventional resin sealing employed for a BOC type CSP is now described with reference to FIG. 11. FIG. 11 is a sectional view showing a finished product, i.e., a package sealed with resin by a conventional resin sealing method and a conventional resin sealing apparatus. As shown in FIG. 11, a semiconductor chip 100 is fixed to a substrate 102 with an adhesive tape 101. A wire 103 electrically connects a pad (not shown) of the semiconductor chip 100 with a pad (not shown) of the substrate 102 through an opening provided in the substrate 102. The pad of the substrate 102 is electrically connected with an external terminal 104, and a solder bump 105, i.e., a protruding electrode is provided on the external terminal 104 for transmitting/receiving signals to/from an external device. Further, the pads provided on the semiconductor chip 100 and the substrate 102 respectively and the wire 103 connecting these pads with each other are covered with sealing resin 106 hardened after potting.
The package shown in FIG. 11 is generally prepared in the following manner: First, the adhesive tape 101 is aligned with and stuck on the substrate 102. Then, the substrate 102 and the semiconductor chip 100 are aligned with each other and thereafter fixed to each other with the adhesive tape 101. Then, the pads of the substrate 102 and the semiconductor chip 100 are electrically connected with each other by wire bonding, i.e., with the wire 103 through the opening of the substrate 102. The opening of the substrate 102 is potted with molten resin for covering a connected portion formed by the pads of the substrate 102 and the semiconductor chip 100 and the wire 103 with a dispenser, and thereafter hardened for forming the sealing resin 106 and sealing the connected portion. Finally, the solder bump 105 is formed on the external terminal 104 of the substrate 102.
According to the conventional resin sealing method and the conventional resin sealing apparatus described above, however, each semiconductor chip 100 is potted with molten resin and hence the efficiency of resin sealing is hard to improve. While the efficiency of resin sealing can be improved by simultaneously using a plurality of dispensers, the resin sealing apparatus is remarkably complicated in this case.
In order to pot the connected portion, further, the viscosity of the molten resin must be reduced to some extent. Therefore, the molten resin spreads to lower dimensional accuracy in resin sealing. Further, the area required for resin sealing is increased to disadvantageously hinder miniaturization of the package.
An object of the present invention is to provide a resin sealing method and a resin sealing apparatus capable of manufacturing a miniature package in high precision by forming a cavity around a connected portion where pads of a semiconductor chip and a substrate are electrically connected with each other by closing molds, injecting molten resin into the cavity and hardening the same thereby efficiently sealing the package with resin.
In order to attain the aforementioned object, a resin sealing method according to an aspect of the present invention, fixing a substrate having an opening to a semiconductor chip with first and second mold portions arranged in a manner where a mold surface of the first mold portion is opposite to a mold surface of the second mold portion, electrically connecting an electrode provided on the semiconductor chip with an electrode provided on the substrate through the opening by a metal conductor including a metal thin wire or a metal strip previously provided on the substrate and thereafter sealing prescribed portions of the substrate and/or the semiconductor chip, comprises steps of placing the substrate on the second mold portion for storing a connected portion including each electrode and the metal conductor in a cavity provided on the mold surface of the first mold portion, closing the first mold portion and the second mold portion for thereafter injecting molten resin into the cavity and hardening the molten resin, and opening the first mold portion and the second mold portion and thereafter taking out the substrate having the semiconductor chip sealed thereto on the connected portion.
According to this method, resin sealing can be performed in excellent dimensional accuracy with a small occupied area by defining a cavity around the connected portion formed by the electrodes of the semiconductor chip and the substrate and the metal thin wire or the metal strip by closing the first and second mold portions, injecting molten resin into the cavity and hardening the same.
In an embodiment of this resin sealing method, the semiconductor chip is further stored in another cavity provided on the mold surface of the second mold portion in the step of placing the substrate on the second mold portion, and the molten resin is injected also into the cavity provided on the mold surface of the second mold portion and hardened in the hardening step.
According to this step, the molten resin is also injected into and hardened in the cavity provided on the second mold portion for storing the semiconductor chip, whereby resin sealing can be performed to cover the semiconductor chip. Therefore, the semiconductor chip can be inhibited from chipping after the resin sealing.
A resin sealing method according to another aspect of the present invention, fixing a plurality of semiconductor chips to a substrate having one or a plurality of openings with first and second mold portions arranged in a manner where a mold surface of the first mold portion is opposite to a mold surface of the second mold portion, electrically connecting electrodes provided on the plurality of semiconductor chips with an electrode provided on the substrate through the opening(s) by a metal conductor including a metal thin wire or a metal strip previously provided on the substrate and thereafter sealing prescribed portions of the substrate and/or each of said semiconductor chip areas, comprises steps of placing the substrate on the second mold portion while directing the plurality of semiconductor chips downward for storing a connected portion including each electrode and the metal conductor in a cavity provided on the mold surface of the first mold portion, closing the first mold portion and the second mold portion for thereafter injecting molten resin into the cavity and hardening the molten resin, and opening the first mold portion and the second mold portion and thereafter taking out the substrate having the plurality of semiconductor chips sealed thereto in each connected portion.
According to this resin sealing method, a plurality of semiconductor chips are fixed to a single substrate and a cavity is defined around the connected portion formed by the electrodes of each semiconductor chip and the substrate and the metal thin wire or the metal strip by closing the first and second mold portions for injecting molten resin into the cavity and hardening the same, whereby resin sealing can be efficiently performed.
In an embodiment of this resin sealing method, the plurality of semiconductor chips are further stored in another cavity provided on the mold surface of the second mold portion in the step of placing the substrate on the second mold portion, and the molten resin is injected also into the cavity provided on the mold surface of the second mold portion and hardened in the step of injecting and hardening the molten resin.
According to this step, the molten resin is also injected into and hardened in the cavity provided on the second mold portion for storing the plurality of semiconductor chips, whereby resin sealing can be performed to cover these semiconductor chips. Therefore, the plurality of semiconductor chips can be inhibited from chipping after the resin sealing.
In this resin sealing method, the molten resin is preferably so injected that pressure in the cavity provided on the mold surface of the second mold portion is higher than pressure in the cavity provided on the mold surface of the first mold portion in the step of injecting and hardening the molten resin.
According to this step, the molten resin injected into the cavity provided on the second mold portion presses the semiconductor chips against the first mold portion, while the cavity of the first mold portion for storing the connected portion is smaller than the cavity of the second mold portion storing the semiconductor chips. Thus, the semiconductor chips and the substrate can be inhibited from deformation resulting from force pressing the semiconductor chips against the first mold portion. Therefore, stress applied to the connected portion of the electrodes of the semiconductor chips and the metal conductor can be reduced for improving reliability of connection.
Thus, the resin sealing method attains an excellent practical effect of efficiently performing resin sealing in excellent dimensional accuracy with a small occupied area while improving reliability after resin sealing.
A resin sealing method according to still another aspect of the present invention, fixing a plurality of substrates each having an opening to a plurality of semiconductor chip areas provided on a wafer respectively with first and second mold portions arranged in a manner where a mold surface of the first mold portion is opposite to a mold surface of the second mold portion, electrically connecting electrodes provided on the semiconductor chip areas with electrodes provided on the substrates through the openings by metal conductors including metal thin wires or metal strips previously provided on the substrates respectively and thereafter sealing prescribed portions of each of the substrates and/or each of the semiconductor chip areas, comprises steps of placing the wafer on the second mold portion for storing a connected portion including each electrode and each metal conductor in a cavity provided on the mold surface of the first mold portion, closing the first mold portion and the second mold portion for thereafter injecting molten resin into the cavity and hardening the molten resin, and opening the first mold portion and the second mold portion and thereafter taking out the wafer in a state sealing prescribed portions of said wafer and/or each of said semiconductor chip areas the substrates to the semiconductor chip areas in each connected portion.
According to this resin sealing method, the plurality of substrates each having an opening are fixed onto the semiconductor chip areas of the wafer respectively and a cavity is defined around the connected portion formed by the electrodes of each semiconductor chip area and each substrate and the metal conductor by closing the fist and second mold portions for injecting the molten resin into the cavity and hardening the same. Therefore, the semiconductor chip areas and the substrates can be more efficiently sealed with the resin in the wafer state.
In an embodiment of this resin sealing method, the plurality of semiconductor chip areas are further stored in another cavity provided on the mold surface of the second mold portion in the step of placing the wafer on the second mold portion, and the molten resin is injected also into the cavity provided on the mold surface of the second mold portion and hardened in the step of injecting and hardening the molten resin.
According to this step, the molten resin is injected also into the cavity provided on the second mold portion for storing the semiconductor chip areas and hardened, whereby resin sealing can be performed to cover the semiconductor chip areas and the semiconductor chip areas can be inhibited from chipping after the resin sealing.
In this resin sealing method, the molten resin is preferably so injected that pressure in the cavity provided on the mold surface of the second mold portion is higher than pressure in the cavity provided on the mold surface of the first mold portion in the step of injecting and hardening the molten resin.
According to this step, the molten resin injected into the cavity provided on the second mold portion presses the semiconductor chip areas against the first mold portion. The cavity of the first mold portion for storing the connected portion is smaller than the cavity of the second mold portion storing the plurality of semiconductor chip areas. Thus, the plurality of semiconductor chip areas and the substrates can be inhibited from deformation resulting from force pressing the semiconductor chip areas against the first mold portion, and stress applied to the connected portion of the electrodes of each of the plurality of semiconductor chip areas and the metal conductor can be reduced for improving reliability of connection.
Thus, the resin sealing method attains an excellent practical effect of efficiently performing resin sealing in excellent dimensional accuracy with a small occupied area while improving reliability after resin sealing.
A resin sealing method according to a further aspect of the present invention, fixing a substrate having a plurality of openings to a wafer having a plurality of semiconductor chip areas with first and second mold portions arranged in a manner where a mold surface of the first mold portion is opposite to a mold surface of the second mold portion, electrically connecting electrodes provided on the semiconductor chip areas with an electrode provided on the substrate through the openings by a metal conductor including a metal thin wire or a metal strip previously provided on the substrate respectively and thereafter sealing prescribed portions of said wafer and/or each of the semiconductor chip areas, comprises steps of placing the wafer on the second mold portion for storing a connected portion including each electrode and the metal conductor in a cavity provided on the mold surface of the first mold portion, closing the first mold portion and the second mold portion for thereafter injecting molten resin into the cavity and hardening the molten resin, and opening the first mold portion and the second mold portion and thereafter taking out the wafer having the substrate sealed thereto on each connected portion.
According to this resin sealing method, the substrate having a plurality of openings is fixed onto the wafer and a cavity is defined around the connected portion formed by the electrodes of each semiconductor chip area and the substrate and the metal conductor by closing the first and second mold portions for injecting the molten resin into the cavity and hardening the same, whereby the semiconductor chip areas and the substrate can be more efficiently sealed with the resin in the wafer state.
A resin sealing apparatus according to a further aspect of the present invention, sealing a semiconductor chip to a substrate having an opening with first and second mold portions arranged in a manner where a mold surface of the first mold portion is opposite to a mold surface of the second mold portion, comprises an first mold portion provided with a cavity on its mold surface for storing a connected portion where an electrode provided on the substrate is electrically connected with an electrode provided on the semiconductor chip through the opening in the cavity, a second mold portion for receiving the semiconductor chip having the substrate fixed thereto, and a resin flowing part for injecting molten resin into the cavity after closing the first mold portion and the second mold portion.
According to this resin sealing apparatus, the semiconductor chip having the substrate fixed thereto is placed on the second mold portion, and the cavity storing the connected portion where the substrate and the semiconductor chip are electrically connected with each other is provided on the first mold portion, and the molten resin is injected into and hardened in the cavity after closing the first and second mold portions. Therefore, the resin hardened in the cavity seals the connected portion in excellent dimensional accuracy with a small occupied area.
A resin sealing apparatus according to a further aspect of the present invention, sealing a semiconductor chip area provided on a wafer to a substrate having an opening with first and second mold portions arranged in a manner where a mold surface of the first mold portion is opposite to a mold surface of the second mold portion, comprises an first mold portion provided with a cavity on its mold surface for storing a connected portion where an electrode provided on the substrate is electrically connected with an electrode provided on the semiconductor chip area through the opening in the cavity, a second mold portion for receiving the wafer having the substrate fixed thereto, and a resin flowing part for injecting molten resin into the cavity after closing the first mold portion and the second mold portion.
According to this resin sealing apparatus, the cavity storing the connected portion where the semiconductor chip area provided on the wafer and the substrate are electrically connected with each other is provided on the first mold portion, and the molten resin is injected into and hardened in the cavity after closing the first and second mold portions. Therefore, the wafer is efficiently sealed with the resin in excellent dimensional accuracy with a small occupied area.
Thus, the resin sealing apparatus attains an excellent practical effect of efficiently performing resin sealing in excellent dimensional accuracy with a small occupied area.
In the resin sealing method and apparatus of the present invention, another cavity for storing said semiconductor chip area may be further provided on the mold surface of the second mold portion, and the resin flowing part may inject the molten resin also into the another cavity provided on the second mold portion.
By means of adopting such a structure, sealing resin is further formed to cover the semiconductor chip area, thereby inhibiting the semiconductor chip area from chipping after resin sealing and, as a result, reliability after resin sealing is further improved.
The foregoing and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings.